144 A MANUAL OF ANATOMY 



closed, as a rule, by the malar, but sometimes by the great wing of 

 the sphenoid, which may here articulate with the superior maxilla. 

 Internally it is bounded by the zygomatic surface of the orbital 

 process of the palate bone. The fissure leads into the orbit, and 

 transmits the superior maxillary nerve to become the infra- 

 orbital, the infra - orbital vessels, the temporo - malar or orbital 

 branch of the superior maxillary nerve, the orbital branches of 

 Meckel's ganglion, and a communicating vein which passes between 

 the inferior ophthalmic vein and the pterygoid plexus. 



The pterygo-maxillary fissure lies vertically between the anterior 

 border of the pterygoid process of the sphenoid and the posterior 

 border of the superior maxilla, at their upper ends. Inferiorly the 

 fissure is closed by the approximation of the bones forming its lips, 

 a part of the tuberosity of the palate bone usually intervening 

 between them, though direct articulation sometimes takes place 

 between the pterygoid process and the superior maxilla. Internally 

 the fissure is bounded by the perpendicular plate of the palate bone. 

 It transmits the internal maxillary artery to the spheno-maxiUary 

 fossa. The pterygo-maxillary fissure meets the spheno-maxillary 

 fissure at a right angle, and situated deeply within this angle is 

 the spheno-maxillary fossa. 



The boundaries of the spheno-maxillary fossa are as follows : 

 anteriorly, the zygomatic surface of the superior maxilla at its 

 inner and back part superiorly ; posteriorly, the base of the 

 pterygoid process of the sphenoid, and the lower and inner part 

 of the anterior surface of its great wing; internally, the perpen- 

 dicular plate of the palate bone, with its orbital and sphenoidal 

 processes ; and superiorly, the under surface of the body of the 

 sphenoid. The contents of the fossa are the third part of the 

 internal maxillary artery, the superior maxillary nerve, and the 

 spheno-palatine or Meckel's ganglion, along with their branches. 

 Two fissures communicate with this fossa, namely, the spheno- 

 maxillary, leading into the orbit, and the pterygo-maxillary, 

 opening into the zygomatic fossa. It also communicates with 

 the, superior meatus of the nose by means of the spheno-palatine 

 foramen on its inner wall. 



The foramina which open into the spheno-maxillary fossa are as 

 follows : three on the posterior wall, in the following order from above 

 downwards, and from without inwards : the foramen rotundum 

 for the superior maxillary nerve, the Vidian or pterygoid canal for 

 the Vidian nerve and vessels, and the pterygo-palatine canal for 

 the pharyngeal nerve and pterygo-palatine vessels. On the 

 internal wall is the splieno-palatine foramen for the internal branches 

 of Meckel's ganglion and the spheno-palatine artery. Inferiorly is 

 the opening of the posterior palatine canal for the great* or anterior 

 descending palatine nerve and the descending palatine artery. 

 In this situation there may also be the openings of the posterior and 

 external accessory palatine canals for the posterior and external 

 descending palatine nerves, but these openings usually branch off 



